<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8" />
		<title></title>
	</head>
	<body>
		<button id="btn1">1</button>
		<input type="button" value="按钮">
		<script type="text/javascript">
			document.querySelector("input[type='button']").value="提交";
		</script>
		<button class="btn2">2</button>
		<button name="btn3">3</button>
		<button>4</button>
		<button>5</button>
		
		<script type="text/javascript">
			var btn1 = document.getElementById("btn1");
			console.log(btn1);
			console.log(btn1.innerHTML);
			btn1.innerHTML="<b>123456</b>";
			btn1.innerText="<b>123456</b>";
			var btn2 = document.getElementsByClassName("btn2")[0];
			console.log(btn2);
			var btn3 = document.getElementsByName("btn3")[0];
			console.log(btn3);
			var btn4=document.getElementsByTagName("button")[3];
			console.log(btn4);
			var btn5=document.querySelector("button:nth-child(5)");
			console.log(btn5);
		</script>
		
		
	</body>
</html>
